Currently 1.3 million people are diagnosed with cancer each year in the United States alone, and over 500,000 die. One method emerging as a new type of treatment for cancer is a type of radiation therapy using an antibody coupled to a therapeutic radionuclide, where the antibody recognizes a target that is specific for a particular type of cancer or found predominantly on cancerous cells. Two examples are currently approved for treatment in the United States: ibitrumomab tiuxetan (ZEVALIN®) and tositumomab (BEXAR®). Ibitrumomab tiuxetan recognizes the CD20 antigen, which is found on normal and malignant B cells. The antibody is coupled to a therapeutic Yttrium-90 radionuclide by a tiuxetan chelator moiety. Tositumomab also recognizes the CD20 antigen, but it is labelled with a I-131 radionuclide. Both are used to treat B-cell non-Hodgkin's lymphoma.
Anti-cancer agents involving toxins, such as diphtheria toxin or Pseudomonas exotoxin, coupled to antibodies that recognize targets found on cancerous cells have also been studied, although no agents of this type are currently approved in the United States.
New agents for treating cancer are needed. Preferably the agents would be targeted to cancer cells and largely spare healthy cells.